Millions of individuals suffer from either partial or total loss of walking ability, resulting in greatly impaired mobility for the afflicted individual. This disabled state can occur as the result of traumatic injury, stroke or other medical conditions that cause disorders that affect muscular control. Regardless of origin, the onset and continuance of walking impairment can cause additional negative physical and/or psychological outcomes for the stricken individual. In order to improve the health and quality of life of patients with walking impairment, the development of devices and methods that can improve or restore walking function is of significant utility to the medical and therapeutic communities. Beyond walking impairment, there are a range of medical conditions that interfere with muscular control of the appendages, resulting in loss of function and other adverse conditions for the affected individual. The development of devices and methods to improve or restore these additional functions is also of great interest to the medical and therapeutic communities.
Human exoskeleton devices are being developed in the medical field to restore and rehabilitate proper muscle function for people with disorders that affect muscle control. These exoskeleton devices include a system of motorized braces that can apply forces to the wearer's appendages. In a rehabilitation setting, exoskeletons are controlled by a physical therapist who uses one of a plurality of possible input means to command an exoskeleton control system. In turn, the exoskeleton control system actuates the position of the motorized braces, resulting in the application of force to, and typically movement of, the body of the exoskeleton wearer. Exoskeleton control systems prescribe and control trajectories in the joints of the exoskeleton. These trajectories can be prescribed as position-based, force-based or a combination of both methodologies, such as that seen in an impedance controller. Position-based control systems can modify exoskeleton trajectories directly through modification of the prescribed positions. Force-based control systems can modify exoskeleton trajectories through modification of the prescribed force profiles. Complicated exoskeleton movements, such as walking, are commanded by the exoskeleton control system through the use of a series of exoskeleton trajectories, with increasingly complicated exoskeleton movements requiring an increasingly complicated series of exoskeleton trajectories. These series of trajectories can be cyclic, such as the exoskeleton taking a series of steps with each leg, or they may be discrete, such as an exoskeleton rising from a seated position into a standing position.
Depending on the particular physiology or rehabilitation stage of a patient, it is often beneficial for a physical therapist to interact with the patient in certain ways prior to the use of the exoskeleton in gait training or other types of rehabilitation. In some cases, patients benefit from a stretching, shaking or other manipulation of the limbs in order to prepare the patient for, and thereby increase the rehabilitative benefit of, exoskeleton therapy. Stretching or other loosening up of the limbs can be particularly important for patients who are unable to control certain muscles. In some cases, the physical therapist will work with patients on improving their balance prior to exoskeleton therapy. Improving patient balance while the patient is standing on one or both legs is of clear benefit to subsequent balance during walking by the patient. There exists an unmet need for ways to utilize an exoskeleton to augment or replace the role of a physical therapist in these pre-gait-training (or “pre-gait”) functions.
In addition, standing for long periods of times can have detrimental effects on the human body, particularly the feet and legs. As a means to ameliorate some of these effects, such as decreased circulation in the feet, a person, when standing for long periods of time, will consciously or subconsciously shift weight from one foot to another. In some cases, a disabled patient using an exoskeleton device may not be able to feel or be aware of certain issues in the legs and feet, and so this patient would be unlikely to shift weight from foot to foot, which is undesirable should the patient remain standing in the exoskeleton for long periods of time in a fixed position. There exists an unmet need for devices and methods that allow exoskeletons to automatically or manually shift the weight of a patient wearing an exoskeleton device in order to prevent injury or discomfort to the patient, thus aiding in the rehabilitation process.
Furthermore, during a gait training session or in certain other types of physical therapy, exact repetitive motions are of lower therapeutic benefit to a patient than varied motions. Robotics-assisted physical therapy, including exoskeleton therapy, is inherently, due to the nature of robotics, predisposed to execution of exact cycles of repetitive motion, and there exists an unmet need to introduce some degree of variability or randomness into the motions executed by exoskeletons in order to increase the therapeutic benefits of these devices.